Recently, with the miniaturization of mobile communication devices, satellite broadcast receiving devices, computers, etc., miniaturization, complexing, high-functionalizing, and high-precisionizing are being advanced for the electronic parts used in these devices and it is required to cope with high densification and high-speed signal transmission in substrate wiring patterns in electronic circuit components.
Also, in recent years, the frequency band of signals used in communication electronic devices is gradually increasing from the MHz band to the GHz band in accordance with the trend of high-functioning electronic devices. Since the electric signal has a characteristic that the transmission loss increases as the frequency increases, a low dielectric constant and low loss coefficient substrate with low dielectric loss in the GHz band and excellent transmission characteristics are requiredin order to cope with such high frequency.
Polymer insulating materials are usually used as substrate materials for printed circuit boards (PCB). In this case, various polymeric insulating materials such as polyolefin resin, epoxy resin, fluorine-based thermoplastic resin, polyimide resin and bismaleimide triazine resin have been proposed. The laminate for a printed circuit board using these materials is made of the polymer material alone or is made by blending the polymer material with glass fiber, nonwoven fabric, inorganic filler, and the like.
Examples of the method for preparing a laminate by mixing the above components include a method in which the polymeric insulating material is dissolved in the organic solvent, impregnated with the glass fabric, and dried, and the prepreg thus obtained and metal foil are superimposed and heated and pressed, and a method in which a polymer insulating material in the case of a polymer insulating material which is insoluble in an organic solvent is melted and processed by a melt injection method to be formed into a plate shape and then superimposed with a metal foil such as a copper foil or an aluminum foil and heated and pressed.
However, in the case of an epoxy resin, which is one of various polymer insulating materials conventionally provided, such an epoxy resin has drawbacks in that it has poor electrical characteristics, especially dielectric loss characteristics in the high frequency range.
Therefore, Korean Patent Publication No. 2015-0060452 discloses a thermosetting resin composition having bisphenol M type epoxy resin, bisphenol M type cyanate ester resin, polyphenylene ether and cross-linkable curing agent as a composition having low dielectric loss characteristics. However, the thermosetting resin composition proposed in this patent has obtained low dielectric characteristics to a certain extent but is not satisfactory in terms of heat resistance.
In addition, Korean Patent Publication No. 2016-0032075 discloses a non-epoxy thermoplastic resin composition in which polyphenylene ether resin is crosslinked using 1,9-decadiene and/or di-4-vinyl benzyl ether.
When the thermoplastic resin composition proposed in the above patent is used as a substrate, although some low dielectric loss characteristics could be obtained, a prepreg made from these compositions was broken during processing or handling and did not exhibit sufficient heat resistance, due to the brittleness properties of the polyphenylene ether resin itself.
Therefore, it is urgent to develop a thermosetting resin composition having excellent heat resistance with low dielectric characteristics.